Internet Edge and WAN Routing with Cumulus Linux

With this article I wanted to focus on something different than the usual spine and leaf topology and talk about datacenter edge routing.

I was using Cisco routers for many years for Internet Edge and WAN connectivity. The problem with using a vendor like Cisco is the price tag you have to pay and there still might a reason for it to spend the money. But nowadays you get leased-lines handed over as normal Ethernet connection and using a dedicated routers maybe not always necessary if you are not getting too crazy with BGP routing or quality of service.

I was experimenting over the last weeks if I could use a Cumulus Linux switch as an Internet Edge and Wide Area Network router with running different VRFs for internet and WAN connectivity. I came up with the following edge network layout you see below:

For this network, I build an Vagrant topology with Cumulus VX to simulate the edge routing and being able to test the connectivity. Below you see a more detailed view of the Vagrant topology:

Everything is running on Cumulus VX even the firewalls because I just wanted to simulate the traffic flow and see if the network communication is functioning. Also having separate WAN switches might be useful because 1Gbit/s switches are cheaper then 40Gbit/s switches and you need additional SFP for 1Gbit/s connections, another point is to separate your layer 2 WAN connectivity from your internal datacenter network.

Here the assigned IP addresses for this lab:

wan-1 VLAN801 PIP: 217.0.1.2/29 VIP: 217.0.1.1/29
wan-2 VLAN801 PIP: 217.0.1.3/29 VIP: 217.0.1.1/29
wan-1 VLAN802 PIP: 10.100.0.1/29 
wan-2 VLAN802 PIP: 10.100.0.2/29
wan-1 VLAN904 PIP: 217.0.0.2/28 VIP: 217.0.0.1/28
wan-2 VLAN904 PIP: 217.0.0.3/28 VIP: 217.0.0.1/28
fw-1 VLAN904 PIP: 217.0.0.14/28
wan-1 VLAN903 PIP: 10.0.255.34/28 VIP: 10.0.255.33/28
wan-2 VLAN903 PIP: 10.0.255.35/28 VIP: 10.0.255.33/28
fw-2 VLAN903 PIP: 10.0.255.46/28
edge-1 VLAN901 PIP: 10.0.255.2/28 VIP: 10.0.255.1/28
edge-2 VLAN901 PIP: 10.0.255.3/28 VIP: 10.0.255.1/28
fw-1 VLAN901 PIP: 10.0.255.14/28
fw-2 VLAN901 PIP: 10.0.255.12/28
edge-1 VLAN902 PIP: 10.0.255.18/28 VIP: 10.0.255.17/28
edge-2 VLAN902 PIP: 10.0.255.19/28 VIP: 10.0.255.17/28
fw-1 VLAN902 PIP: 10.0.255.30/28

You can find the Github repository for the Vagrant topology here: https://github.com/berndonline/cumulus-edge-vagrant

[email protected]:~/cumulus-edge-vagrant$ vagrant status
Current machine states:

fw-2                      running (libvirt)
fw-1                      running (libvirt)
mgmt-1                    running (libvirt)
edge-2                    running (libvirt)
edge-1                    running (libvirt)
wan-1                     running (libvirt)
wan-2                     running (libvirt)

This environment represents multiple VMs. The VMs are all listed
above with their current state. For more information about a specific
VM, run `vagrant status NAME`.
[email protected]:~/cumulus-edge-vagrant$

I wrote as well an Ansible Playbook to deploy the initial configuration which you can find here: https://github.com/berndonline/cumulus-edge-provision

Let’s execute the playbook:

[email protected]:~/cumulus-edge-vagrant$ ansible-playbook ../cumulus-edge-provision/site.yml

PLAY [edge] ********************************************************************************************************************************************************

TASK [switchgroups : create switch groups based on clag_pairs] *****************************************************************************************************
skipping: [edge-2] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [edge-1] => (item=(u'wan', [u'wan-1', u'wan-2']))
ok: [edge-2] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [wan-1] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [wan-1] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [edge-1] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [wan-2] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [wan-2] => (item=(u'edge', [u'edge-1', u'edge-2']))

TASK [switchgroups : include switch group variables] ***************************************************************************************************************
skipping: [edge-2] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [edge-1] => (item=(u'wan', [u'wan-1', u'wan-2']))
ok: [wan-1] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [wan-1] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [wan-2] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [wan-2] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [edge-2] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [edge-1] => (item=(u'edge', [u'edge-1', u'edge-2']))

...

RUNNING HANDLER [interfaces : reload networking] *******************************************************************************************************************
changed: [edge-2] => (item=ifreload -a)
changed: [edge-1] => (item=ifreload -a)
changed: [wan-1] => (item=ifreload -a)
changed: [wan-2] => (item=ifreload -a)
changed: [edge-2] => (item=sleep 10)
changed: [edge-1] => (item=sleep 10)
changed: [wan-2] => (item=sleep 10)
changed: [wan-1] => (item=sleep 10)

RUNNING HANDLER [routing : reload frr] *****************************************************************************************************************************
changed: [edge-2]
changed: [wan-1]
changed: [wan-2]
changed: [edge-1]

RUNNING HANDLER [ptm : restart ptmd] *******************************************************************************************************************************
changed: [edge-2]
changed: [edge-1]
changed: [wan-2]
changed: [wan-1]

RUNNING HANDLER [ntp : restart ntp] ********************************************************************************************************************************
changed: [wan-1]
changed: [edge-1]
changed: [wan-2]
changed: [edge-2]

RUNNING HANDLER [ifplugd : restart ifplugd] ************************************************************************************************************************
changed: [edge-1]
changed: [wan-1]
changed: [edge-2]
changed: [wan-2]

PLAY RECAP *********************************************************************************************************************************************************
edge-1                     : ok=21   changed=17   unreachable=0    failed=0
edge-2                     : ok=21   changed=17   unreachable=0    failed=0
wan-1                      : ok=21   changed=17   unreachable=0    failed=0
wan-2                      : ok=21   changed=17   unreachable=0    failed=0

[email protected]:~/cumulus-edge-vagrant$

At last but not least I wrote a simple Ansible Playbook for connectivity testing using ping what you can find here: https://github.com/berndonline/cumulus-edge-provision/blob/master/icmp_check.yml

[email protected]:~/cumulus-edge-vagrant$ ansible-playbook ../cumulus-edge-provision/check_icmp.yml

PLAY [exit edge] *********************************************************************************************************************************************************************************************************************

TASK [connectivity check from frontend firewall] *************************************************************************************************************************************************************************************
skipping: [fw-2] => (item=10.0.255.33)
skipping: [fw-2] => (item=10.0.255.17)
skipping: [fw-2] => (item=10.0.255.1)
skipping: [fw-2] => (item=217.0.0.1)
skipping: [edge-2] => (item=10.0.255.33)
skipping: [edge-2] => (item=10.0.255.17)
skipping: [edge-2] => (item=10.0.255.1)
skipping: [edge-1] => (item=10.0.255.33)
skipping: [edge-2] => (item=217.0.0.1)
skipping: [edge-1] => (item=10.0.255.17)
skipping: [edge-1] => (item=10.0.255.1)
skipping: [wan-1] => (item=10.0.255.33)
skipping: [edge-1] => (item=217.0.0.1)
skipping: [wan-1] => (item=10.0.255.17)
skipping: [wan-1] => (item=10.0.255.1)
skipping: [wan-1] => (item=217.0.0.1)
skipping: [wan-2] => (item=10.0.255.33)
skipping: [wan-2] => (item=10.0.255.17)
skipping: [wan-2] => (item=10.0.255.1)
skipping: [wan-2] => (item=217.0.0.1)
changed: [fw-1] => (item=10.0.255.33)
changed: [fw-1] => (item=10.0.255.17)
changed: [fw-1] => (item=10.0.255.1)
changed: [fw-1] => (item=217.0.0.1)
...
PLAY RECAP ***************************************************************************************************************************************************************************************************************************
edge-1                     : ok=2    changed=2    unreachable=0    failed=0
edge-2                     : ok=2    changed=2    unreachable=0    failed=0
fw-1                       : ok=1    changed=1    unreachable=0    failed=0
fw-2                       : ok=1    changed=1    unreachable=0    failed=0
wan-1                      : ok=2    changed=2    unreachable=0    failed=0
wan-2                      : ok=2    changed=2    unreachable=0    failed=0

[email protected]:~/cumulus-edge-vagrant$

The icmp check shows that in general the edge routing is working but I need to do some further testing with this if this can be used in a production environment.

If using switch hardware is not the right fit you can still install and use Free Range Routing (FRR) from Cumulus Networks on other Linux distributions and pick server hardware for your own custom edge router. I would only recommend checking Linux kernel support for VRF when choosing another Linux OS. Also have a look at my article about Open Source Routing GRE over IPSec with StrongSwan and Cisco IOS-XE where I build a Debian software router.

Please share your feedback and leave a comment.

Getting started with Jenkins for Network Automation

As I have mentioned my previous post about Getting started with Gitlab-CI for Network Automation, Jenkins is another continuous integration pipelining tool you can use for network automation. Have a look about how to install Jenkins: https://wiki.jenkins.io/display/JENKINS/Installing+Jenkins+on+Ubuntu

To use the Jenkins with Vagrant and KVM (libvirt) there are a few changes needed on the linux server similar with the Gitlab-Runner. The Jenkins user account needs to be able to control KVM and you need to install the vagrant-libvirt plugin:

usermod -aG libvirtd jenkins
sudo su jenkins
vagrant plugin install vagrant-libvirt

Optional: you may need to copy custom Vagrant boxes into the users vagrant folder ‘/var/lib/jenkins/.vagrant.d/boxes/*’. Note that the Jenkins home directory is not located under /home.

Now lets start configuring a Jenkins CI-pipeline, click on ‘New item’:

This creates an empty pipeline where you need to add the different stages  of what needs to be executed:

Below is an example Jenkins pipeline script which is very similar to the Gitlab-CI pipeline I have used with my Cumulus Linux Lab in the past.

pipeline {
    agent any
    stages {
        stage('Clean and prep workspace') {
            steps {
                sh 'rm -r *'
                git 'https://github.com/berndonline/cumulus-lab-provision'
                sh 'git clone --origin master https://github.com/berndonline/cumulus-lab-vagrant'
            }
        }
        stage('Validate Ansible') {
            steps {
                sh 'bash ./linter.sh'
            }
        }
        stage('Staging') {
            steps {
                sh 'cd ./cumulus-lab-vagrant/ && ./vagrant_create.sh'
                sh 'cd ./cumulus-lab-vagrant/ && bash ../staging.sh'
            }
        }
        stage('Deploy production approval') {
            steps {
                input 'Deploy to prod?'
            }
        }
        stage('Production') {
            steps {
                sh 'cd ./cumulus-lab-vagrant/ && ./vagrant_create.sh'
                sh 'cd ./cumulus-lab-vagrant/ && bash ../production.sh'
            }
        }
    }
}

Let’s run the build pipeline:

The stages get executed one by one and, as you can see below, the production stage has an manual approval build-in that nothing gets deployed to production without someone to approve before, for a controlled production deployment:

Finished pipeline:

This is just a simple example of a network automation pipeline, this can of course be more complex if needed. It should just help you a bit on how to start using Jenkins for network automation.

Please share your feedback and leave a comment.

Ansible Automation with Cisco ASA Multi-Context Mode

I thought I’d share my experience using Ansible and Cisco ASA firewalls in multi-context mode. Right from the beginning I had a few issues deploying the configuration and the switch between the different security context didn’t work well. I got the error you see below when I tried to run a playbook. Other times the changeto context didn’t work well and applied the wrong config:

[email protected]:~$ ansible-playbook -i inventory site.yml --ask-vault-pass
Vault password:

PLAY [all] ***************************************************************************************************************************************************************************

TASK [hostname : set dns and hostname] ***********************************************************************************************************************************************
An exception occurred during task execution. To see the full traceback, use -vvv. The error was: error: [Errno 61] Connection refused
fatal: [fwcontext01]: FAILED! => {"changed": false, "err": "[Errno 61] Connection refused", "msg": "unable to connect to socket"}
ok: [fwcontext02]

TASK [interfaces : write interfaces config] ******************************************************************************************************************************************
ok: [fwcontext02]

....

After a bit of troubleshooting I found a workaround to limit the amount of processes Ansible use and set this limit to one in the Ansible.cfg. The default is five processes if forks is not defined as far as I remember.

[defaults]
inventory = ./inventory
host_key_checking=False
jinja2_extensions=jinja2.ext.do
forks = 1

In the example inventory file, the “inventory_hostname” variable represents the security context and as you see the “ansible_ssh_host” is set to the IP address of the admin context:

fwcontext01 ansible_ssh_host=192.168.0.1 ansible_ssh_port=22 ansible_ssh_user='ansible' ansible_ssh_pass='cisco'
fwcontext02 ansible_ssh_host=192.168.0.1 ansible_ssh_port=22 ansible_ssh_user='ansible' ansible_ssh_pass='cisco'

When you run the playbook again you can see that the playbook runs successfully but deploys the changes one by one to each firewall security context, the disadvantage is that the playbook takes much longer to run:

[email protected]:~$ ansible-playbook site.yml

PLAY [all] ***************************************************************************************************************************************************************************

TASK [hostname : set dns and hostname] ***********************************************************************************************************************************************
ok: [fwcontext01]
ok: [fwcontext02]

TASK [interfaces : write interfaces config] ******************************************************************************************************************************************
ok: [fwcontext01]
ok: [fwcontext02]

Example site.yml

---

- hosts: all
  connection: local
  gather_facts: 'no'

  vars:
    cli:
      username: "{{ ansible_ssh_user }}"
      password: "{{ ansible_ssh_pass }}"
      host: "{{ ansible_ssh_host }}"

  roles:
    - interfaces

In the example Interface role you see that the context is set to “inventory_hostname” variable:

---

- name: write interfaces config
  asa_config:
    src: "templates/interfaces.j2"
    provider: "{{ cli }}"
    context: "{{ inventory_hostname }}"
  register: result

- name: enable interfaces
  asa_config:
    parents: "interface {{ item.0 }}"
    lines: "no shutdown"
    match: none
    provider: "{{ cli }}"
    context: "{{ inventory_hostname }}"
  when: result.changed
  with_items:
    - "{{ interfaces.items() }}"

After modifying the forks, the Ansible playbook runs well with Cisco ASA in multi-context mode, like mentioned before it is a bit slow to deploy the configuration if I compare this to Cumulus Linux or any other Linux system.

Please share your feedback.

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